Even though threats and other actions by terrorist and fringe groups have occurred with biological, germ, chemical, or other harmful agents over the years, more recent developments have brought such threats to the forefront of the public thought and action. Postal and delivery firms, however, continue to face significant problems with biological, germ, chemical, and other harmful agents that are likely to cause injury, sickness, or death when handled by the transportation or delivery firm or when opened by the intended recipient of a mailpiece or package. The U.S. Postal Service (USPS) has declared that safety of all people processing, delivering and receiving mail must be given the highest priority.
The complexity of detection of contents of a letter, flat, or package within the USPS or other mail or parcel delivery service is immense. The USPS, for example, handles over 680 million pieces of mail every day collected from as many as 100 million points (assuming residential and businesses may leave mail for the delivery carrier to pick up). In the U.S. alone, there are up to 500 processing centers collecting mail from over 28,000 post offices which, in turn, collect mail from mail drops or collection boxes that easily number over one million. It can be practically impossible to have personalized inspectors located at each mail drop or collection box. For example, the cost can be prohibitive, the environments are not well controlled, and mail drop or other mail boxes can be subject to bypass by handling mail directly to a delivery carrier.
Also, in the USPS, there are three primary types of mail categories. For example, letters and postcards are, by USPS definition, no larger than 6.125 inches by 11.5 inches or ¼ inch thick. Flats are larger than letters but no larger than 12 inches by 15 inches or 1.25 inches thick. Parcels are any mailpiece that exceeds a flat dimension. Letters are typically processed by different equipment than flats or parcels due to the difference in the physical characteristics. Accordingly, because of the different sizes, shapes, and weight of mail and the different processing stations within postal service companies, detecting biological, germ, chemical, and other harmful agents within the mail can be even more difficult. Further, to add to the complexity, as described above, mail and mail packaging also can be composed of different materials other than just paper or organic products which, in turn, makes it even more difficult to process and handle.